Liquid displacement pumps



Sept. 3, 1968 T. J. SKINNER 3,399,625

LIQUID DISPLACEMENT PUMPS Filed Aug. 25, 1966 United States Patent3,399,625 LIQUID DISPLACEMENT PUMPS Robert Thomas John Skinner,Kenilworth, England, assignor to Joseph Lucas (Industries), Limited,Birmingham, England, a British company Filed Aug. 23, 1966, Ser. No.574,347 2 Claims. (Cl. 103-97) ABSTRACT OF THE DISCLOSURE A liquiddisplaceemnt pump comprising a body with an interior cavity, a bladedrotor in the cavity, an inlet and an outlet at positions spaced aroundthe rotor periphery, a part annular recess in the wall of the cavityextending around the rotor periphery between the inlet and outlet, apiston defining the base of the recess, and means responsive to thepressure in the pump outlet for moving the piston to vary the volume ofthe recess.

This invention relates to liquid displacement pumps of the kind having abody, a bladed rotor mounted within a cavity in the body, an inlet andan outlet at positions spaced from one another around the rotor, and apartannular recess defined in the wall of the cavity in the body, saidrecess extending around the periphery of the rotor between the positionof the inlet and that of the outlet.

The object of the present invention is to provide a liquid displacementpump of the kind specified in a convenient form.

A liquid displacement pump according to the present invention has thebase of the part annular recess and movable towards and away from therotor, and liquid pressure operable means responsive to the pressure ofliquid in the pump outlet for moving said piston towards the rotor toreduce the volume of the recess.

The invention will now be described by way of example with reference tothe accompanying drawings in which:

FIGURE 1 is a cross-sectionable view of a pump to which the invention isapplied.

FIGURE 2 is a fragmentary view of part of the pump illustrating one formof the invention.

FIGURES 3 and 4 show alternative controls for the pump.

In the example shown in FIGURE 1 there is provided a liquid displacementpump which is suitable for supplying fuel to an internal combustionengine. The pump has a body which defines a generally cylindricalinternal cavity 11 within which is mounted a bladed rotor 12 connectedto a shaft 13 which can be driven by the engine to which the pump isintended to supply fuel. The rotor blades, in this example, extendradially and can sweep the whole of the cavity 11, and in thecylindrical wall are a pair of diametrically opposite tangential outletsone of which is shown at 9.

One side wall of the cavity 11 is formed by an inlet plate 14 defining apair of inlet openings 15 which communicates through an impeller 15awith an inlet port 16 formed in a part 17 secured to the pump body 10.The inlets 15 (one of which is shown only) are spaced angularly from theoutlets 9 respectively.

The opposite side wall of the cavity 11 has an annular recess 18 ofchannel shape in cross-section and this is divided by a pair of fixedabutments 19a into a pair of semi-circular recesses, each of whichextends between the position of one of the inlets and that of anassociated outlet, the recess 18 being at the outer edge of the cavity11 and the radial width of the recess 18 being approximately a quarterof the radius of the rotor 12.

The base walls of the portions of recess 18 are formed by the crown ofan annular piston 19 disposed in an annular chamber 20 within the body10, the piston 19 having two cavities 19b in its crown for accommodationof the fixed abutments 19a.

Communicating with the outlets 9 of the pump is a by-pass passage 21including a fixed restrictor 22, the passage 21 communicating with twofurther passages 23, 24, one of which leads to the space at the oppositeend of the piston 19 from the rotor 12, and the other of which leads toan outlet 25 controlled by a member 26, the pressure in the passage 23thus determining the movement of the piston 19 to reduce the volume ofthe recess 18. The forces acting upon the piston to maintain it at theextremity of its travel remote from the rotor 12 are provided by springs19c and by the pressure of liquid in the recesses between the inlets andoutlets, the latter pressure increasing from the inlet to the outlet ineach case.

By varying the setting of the member 26, the movement of the piston canbe varied in accordance with requirements. Cam means 26a is provided forcontrolling the member 26.

FIGURE 3 shows an alternative form of control in which the by-passpassage 21 from the pump outlet has a discharge orifice 27 arrangedadjacent to a receiving orifice 28 at the end of the passage 23 to thechamber 20 behind the piston 19. Between the two orifices 27, 28 is aknife 29, the position of which is controlled as desired by an externalcam means 29a against a spring 30. The orifices 27, 28 are disposed inan enclosure 31 having a drain passage 32.

In FIGURE 4 is shown a further form of control in which the by-passpassage 21 from the pump outlet communicates, at the point of pivotalmounting, with the interior of a hollow lever 33. This lever iscontrolled against a spring 34 by a cam 35 and arm 35a. A dischargenozzle 36 at the free end of the lever 33 is arranged to discharge intoa receiving nozzle 37 at the end of the passage 23 leading to thechamber 20. The parts are disposed in an enclosure 38 having a drainpassage 39. It will be understood that other forms of control can beused to obtain similar results. The control of the member 26, the knife29 or the lever 33 can be achieved by any suitable parameter or manuallyas desired.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid displacement pump having a body, a bladed rotor mountedwithin a cavity in the body, an inlet and an outlet at positions spacedfrom one another around the rotor, a part annular recess defined in thewall of the cavity in the body, said recess extending around theperiphery of the rotor between the position of the inlet and that of theoutlet, a piston defining the base of the part annular recess andmovable towards and away from the rotor, and liquid pressure operablemeans responsive to the pressure of liquid in the pump outlet for movingsaid piston towards the rotor to reduce the volume of the ReferencesCited mess- UNITED STATES PATENTS 2. A liquid displacement pump asclaimed in claim 1 in which the liquid pressure operable means comprises1768242 6/1930 Ferguson 103 96 a control whereby the pressure in achamber at the side 5 2,039,815 5/1936 Lupter 1O396 of the piston remotefrom the rotor can be varied in ac- 2,957,424 10/1960 Brundage 103-97cordance with the pressure in the pump outlet and also I accordance withat least one other factor. ROBERT WALKER Prlma'y Examme'

